Air bag-equipped child&#39;s vehicle seat and alarm/arming system therefore

ABSTRACT

A child&#39;s seat for use in motor vehicles, including an air bag and activation circuitry. Sensors on the seat emit a first signal confirming that the air bag is armed and that the seat belt is properly connected. A second warning signal is produced when the child&#39;s seat air bag is not properly functioning or if the child&#39;s seat is not properly held in place by the vehicle&#39;s seat belt system. Also disclosed is an air bag inflator including a pressure tank, a frangible membrane for sealing gas under pressure within the tank, and a pyrotechnic squib for rupturing the frangible membrane to deploy the air bag.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of application Ser. No. 08/276,179, filed Jul.15, 1994 which is a continuation-in-part of application of Ser. No.08/092,725, filed Jul. 16, 1993 now abd.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to the field of infant and child safetyseating for motor vehicles and, more particularly, to such seating whichis equipped with an alarm and/or air bag system for delivering anotification signal that the seat is properly installed and further,that the air bag is functional. The invention further relates to an airbag inflator which does not generate heat, toxic gas or residue duringair bag deployment.

2. Detailed Description of the Related Art

The value of child car seats in saving lives has been proven to thedegree that it has now been mandated, through legislation, that allchildren under the age of three years must be restrained in a child'sseat while the vehicle is in motion.

Virtually all child's car seats are secured to the vehicle by employingthe adult seat belts (lap belts) which are fastened around the child'scar seat and are buckled.

Unfortunately, even with the use of child's car seats, thousands ofchildren are injured or killed annually because the car seat isimproperly installed. For example, when parents remove the car seat toclean the vehicle, or transfer the car seat to another vehicle, it ispossible that the parent will forget to refasten the seat belt. Inaddition, it is possible, even when the belt end is inserted into thebuckle, that a secure locking connection therebetween may not have beenmade. Another possible failure in the seat belt securing system lies inthe accidental separation of the buckle from the belt. This can occur asthe result of shifting cargo or a passenger bumping into the buckle, ora child playing with the buckle.

Child's car seats have been proposed that include an air bag in order tofurther protect the child from injury in event of a serious collision.One air bag equipped car seat is disclosed in U.S. Pat. No. 4,834,420 toSankrithi et al. While such seat affords potentially enhancedprotection, no provision is made for ensuring that the air bag is armedand is operating properly. Specifically, the apparatus taught bySankrithi et al requires that a computer be operable in order for thedevice to function properly. Electrical power must, therefore, besupplied to the computer and whether supplied by battery or directlyfrom the vehicle's power supply, the lack of power will render anotherwise beneficial safety system ineffective.

An important element of an air bag system is a gas generator orinflator. Current air bag inflators employ pyrotechnic technology(sodium azide/potassium nitrate), which is ill-suited for a vehicularchild safety and restraint system for several reasons. In particular,heat produced by the combustion of gas-generating propellant materialsis excessive. Moreover, due to uncontrollable variables in propellantloading, such as mixture ratio, aging, moisture content, and unevenburning, a dynamically filled air bag system is required. Thus, adynamic air bag has vents which emit jets of scalding hot gases duringdeployment. Still further, sodium azide, conventionally used in thepropellant for pyrotechnic inflators, is extremely toxic to humans andanimals. It will be appreciated that, in a child safety restraintsystem, the relatively close proximity of the child to the gas generatorgreatly enhances all of these concerns.

Further, sodium azide is extremely flammable and toxic, and must behandled in a clean room environment under carefully controlledconditions. Such increases the manufacturing costs. Moreover, recentlythe life expectancy of sodium azide inflators has been questioned.

It would, therefore, be a substantial advance in the art to provide achild's car seat that includes an alarm for indicating improperinstallation of the seat, particularly with respect to the seat tovehicle connection and the arming of the air bag.

It would further be an advance in the art to provide an improvedinflator for an air bag, particularly for use in a vehicular childsafety and restraint system.

It is, therefore, an object of the present invention to provide animproved child's car seat.

Another object off the present invention is to provide an improvedchild's safety car seat of enhanced safety character.

Yet another object of the present invention is to provide a child's carseat having improved reliability.

A still further object of the present invention is to provide a child'scar seat including an alarm for indicating the improper installationthereof.

A still further object of the present invention is to provide a child'scar seat that indicates that the child's car seat air bag is armed.

It is yet another object of the invention to provide an improved air baginflator, particularly for a vehicular child safety and restraintsystem, which eliminates any burn hazard or toxic material hazard, andwhich has long term reliability.

Other objects and advantages will be more fully apparent from theensuing disclosure and appended claims.

SUMMARY OF THE INVENTION

The foregoing objects of the present invention are accomplished byproviding a child's seat of a type adapted to be attached to a vehicleseat (such as a motor vehicle, air craft, or boat) by fastening thevehicle's seat belt system thereto. The child's seat of the presentinvention features an inflatable air bag system which is stored in acollapsed state within the child's seat means and is selectively rapidlyexpandable in order to protect a child seated in the child's seat frominjury upon sudden deceleration of the vehicle. The air bag system isarmed via a sensor mounted to the child seat. The sensor is positionedin sensing relation to a child positioned in the child's seat such thatthe air bag is armed when a child is positioned therewithin and isdisarmed when the child is removed therefrom. The child's seat alsoincludes a second sensor for indicating the status of the seat beltholding the child's seat in place on the vehicle seat. The second sensoris positioned in operative association with the seat belt system andsenses whether the seat belt system is in locking engagement or not. Afirst signal is emitted when the seat belt system is in lockingengagement and a second warning signal is emitted when the seat beltsystem is in an unlocked (disengaged) state.

In another form, the invention provides a vehicular child safety andrestraint system including a seat structure, an air bag system includingan inflatable air bag and an inflator, a child restraining harness, aharness switch activated when the child is secured within the harness,and a connection for arming the air bag system when the harness switchis activated and for disarming the air bag system when the harnessswitch is deactivated. There is further provided a buttocks switchpositioned within the seat structure so as to be activated upon properpositioning of a child within the seat structure, and a device forissuing a warning indicating that the child is escaping when the harnessswitch is activated and the buttocks switch is deactivated. At least oneseat belt sensing switch is in operative association with the seatstructure and the seat belt system of a vehicular seat belt systemfastened to the child safety and restraint system, the seat belt sensingswitch being activated when the seat belt system is in lockingengagement. A device is provided for issuing a warning indicating thatthe seat belt system is not in locking engagement when the harnessswitch is activated and the seat belt sensing switch is deactivated.Further, a device is provided for emitting a status signal indicatingthat the child is safe when the harness switch, the buttocks switch andthe seat belt sensing switch are all activated.

Another aspect of the invention is the provision of an inflator for theair bag, the inflator including a pressure tank having an outletconnected to the inflatable air bag and containing gas under pressure.At least one frangible membrane is arranged for sealing the gas underpressure within the tank, and a controllable device, such as apyrotechnic device, is positioned for rupturing the frangible membranefor inflating the inflatable air bag by allowing gas under pressure toflow from the tank into the air bag. Preferably there are a pair offrangible membranes spaced from each other and arranged in series forsealing the gas under pressure within the tank. The pyrotechnic deviceis positioned between the frangible membranes, rendering the pyrotechnicdevice essentially inaccessible to inhibit tampering.

The air bag system is contained within an enclosure having a door whichopens when the inflatable air bag inflates and which defines an openingthrough which the inflatable air bag projects in a deployed position. Anacceleration sensor is connected to the air bag system for activatingthe air bag system upon the sensing of acceleration forces indicative ofa collision. In addition, to discourage tampering there is ananti-tamper safety switch connected to the door and to the air bagsystem for activating the air bag system upon the opening of the door,thereby making it readily apparent when a person has attempted to tamperwith the air bag system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a child's car seat according to oneembodiment of the present invention.

FIG. 2 is a side view of a child's car seat according to one embodimentof the invention, as installed in a motor vehicle.

FIG. 3 is a side view of a child's car seat according to one embodimentof the present invention, as installed in a motor vehicle and showingthe air bag inflated.

FIG. 4 is a side view of an alternative embodiment according to thepresent invention, of a restraining system for larger children, with theair bag inflated.

FIG. 5 is a side view of a child's booster seat installed in a vehiclewith an air bag and alarm according to another embodiment of the presentinvention.

FIG. 6 is an electrical schematic diagram of an alarm and air bag armingsystem in accordance with a preferred embodiment of the presentinvention.

FIG. 7 is a broken away plan view of the swing-down arm of a child's carseat according to one embodiment of the present invention, showing theair bag and alarm systems installed therein.

FIG. 8 is a schematic representation of a car seat/air bag systemaccording to another aspect of the present invention.

FIG. 9 is a perspective view, comparable to FIG. 1, of an alternativephysical configuration of a child's car seat according to another aspectof the invention.

FIG. 10 is a side view of the child's car seat of FIG. 9, as installedin a motor vehicle and showing the air bag inflated or deployed.

FIG. 11A depicts a harness lock plate and FIG. 11B depicts a slidingharness lock mechanism including the harness switch of the child safetyseat of FIGS. 9 and 10.

FIG. 12 is an exploded view showing the manner in which an air bagsystem fits into the swing down shield of the child's safety seatstructure of FIGS. 9 and 10.

FIG. 13 is an enlarged view of a portion of the inflator included in theFIG. 12 air bag system.

FIG. 14 is an electrical schematic diagram of circuitry included withinthe seat structure of FIGS. 9 and 10.

DETAILED DESCRIPTION OF THE INVENTION AND ILLUSTRATIVE EMBODIMENTSTHEREOF

While the present invention will be described more fully hereinafterwith reference to the accompanying drawings, in which particularembodiments are shown, it is to be understood at the outset that personsskilled in the art may modify the invention herein described while stillachieving the functions and results of this invention. Accordingly, thedescription which follows is to be understood as illustrative andexemplary of specific structures, aspects and features within the broadscope of the present invention and not as limiting of such broad scopeof the present invention.

Referring now to the drawings and particularly to FIGS. 1 through 3, achild safety and restraint system in the form of a child's car seatgenerally indicated at 10 is therein illustrated. The car seat comprisesa child seating means or seat structure such as a molded plastic shell12 having a cavity 14 generally in a shape so as to comfortably allow achild C to be seated therein. A padded liner 16 is positioned within thecavity and provides a comfortable surface for the child to rest on. Theliner 16 is usually detachably fastened to the shell 12 via mechanicalfastening means such as a combination of straps, hook and loopfasteners, and snaps (not shown). Located near the lower portion of thecar seat 10 is a bar 20 that is used to adjust the angle of the child'scar seat relative to the angle of the vehicle seat to which it isconnected in order that the child C is essentially forward facing in acomfortable position. A swing down shield 22 comprises a padded centralportion 24 and a pair of opposing outwardly extending arms 26 which arehingedly secured at 28 to the main portion of the shell 12. The swingdown shield 22 is adapted to swing from a substantially verticalupwardly extended position that allows the child unrestricted movement(such as positioning of the child in and removal of the child from theseat 10), to a locked position wherein the swing down shield 22 isessentially forward facing. Connected to the swing down shield 22 are apair of webbed shoulder straps 30 that further restrain the child whenthe swing down shield 22 is engaged. Each of the shoulder straps has oneof its ends connected to the swing down shield 22 and the opposite endis inserted through one set of holes defining openings 32,34, dependingon which set is appropriate for the child's size, and is connected tothe rear of the seat by suitable means (not shown).

The car seat 10 is fastened to the vehicle seat by means of a seat beltsystem which is passed behind the seat and through slot openings 36 onopposite sides of the shell 12. The seat belt end is then inserted intothe buckle so that it is locked in place. The seat belt and buckle arecollectively referred to as the seat belt system S. Also provided is alocking mechanism 38 that locks the swing down shield 22 to the shell 12in the forward facing position.

FIGS. 4 and 5 illustrate different types of safety seating which couldbe equipped with the air bag and alarm of the present invention. Forexample, FIG. 4 illustrates an air bag system that is incorporated intoa swing shield restraining system and FIG. 5 illustrates an air bagsystem incorporated into a child's booster seat. In the description thatfollows reference will be specifically made to the child's seat of FIGS.1-3. However, the reader will appreciate that the system described couldbe readily applied to the child's seat of FIGS. 4 and 5, as well asothers not herein illustrated.

FIG. 7 illustrates a broken away plan view of the swing down shield 22of the car seat. The inflatable air bag means or air bag 40 andassociated circuitry and sensors may also be stored therein and areschematically indicated at 42.

Air bag systems such as would be adapted for use in the presentinvention include an expandable air bag having a shuttle valve connectedthereto. A tank 2 of pressurized gas (e.g., compressed air at a pressureof 150 psi) or any one of the well known chemical gas generating systemsis connected to the shuttle valve 3. A solenoid valve is connected tothe gas generator and is activated by sensing means such as an inertialswitch, or, more preferably, an accelerometer, which is powered by thevehicle power source or, more preferably a battery within the seathousing. A detailed explanation of the air bag system is not deemednecessary because the technology is well developed for use inautomobiles and is easily adapted for use in connection with the presentinvention, within the skill of the relevant art.

The air bag 40 is stored in a collapsed state (as shown in FIG. 7)within the child seating means and particularly within the swing downbar 22. The air bag 40 is adapted to expand in order to protect frominjury a child C seated (or otherwise positioned) within the child'sseat upon sudden deceleration of the vehicle, such as occurs during acollision.

The child's seat 10 includes an air bag arming system for arming the airbag 40 mounted to the child's seating means and positioned in sensingrelation to the child C positioned therewithin. The air bag 40 is armedwhen the child C is positioned in the child seating means or shell 12and is disarmed when the child is removed therefrom. The air bag armingsystem is activatable by positioning the child in the shell 12. In thepreferred embodiment, the system for arming the air bag 40 comprises aswitch means or switch 46 (see the schematic circuit diagram of FIG. 6)that is mounted in the shell 12 so that the switch is open when theshell is vacant and is closed by the weight of the child C being placedtherein. In the illustrated embodiment, the switch 46 is located in thelower portion of the shell 12 and is closed when the child's bottomcontacts the shell. The foregoing is a preferred location for the switchdue to the fact that it will remain closed should the child leanforward.

Turning now to another aspect of the invention, child's safety seats arevirtually useless when not properly installed within the vehicle, i.e.,the seat belt system S must be connected so that the belt and the buckleare in locking engagement in order to assure that the child's seat 10 isheld in place in the event of a collision. Thus, the present inventionincludes a seat belt sensing means 50 for sensing that the seat beltsystem is properly engaged or locked. The seat belt sensing means 50 ispositioned in operative association with the child seating means or seatstructure 10. In the preferred embodiment the seat belt sensing means 50includes a second switch means or switch 52 that is connected to theshell 12 such that the seat belt system S is in contacting relationtherewith. When the seat belt system S exerts a pressure on the switch52 sufficient to close or activate the switch 52, the seat belt system Sis in locking engagement and emits a first signal confirming properinterconnection of the seat belt and the buckle. The switch 52 isdeactivated upon unlocking disengagement of the seat belt system S and asecond warning signal is emitted. In the illustrated embodiment, theswitch 52 is positioned within one of belt slot openings 36 such thatwhen the belt is placed over switch 52 and is placed in tension, switch52 is closed. The reader will note that although a switch location issuggested, it could nevertheless be located elsewhere without adverselyaffecting the operation of the present invention.

Referring again to FIG. 6, a DC power source 65 such as a separatebattery or a battery power supply means of the vehicle itself provideselectrical power to the circuit in line 54a. Switch 46 is employed toarm the air bag and has one of its contacts connected to the electricalpower source at 54a and its opposite contact connected on line 46a to aninertial switch 56 that closes upon impacts greater than one-half theforce of gravity (0.5 g). The inertial switch 56 may suitably comprisean Analog Devices ADXL50 accelerometer along with associated electronicscircuitry as necessary to energize the solenoid valve in the event of acrash. Switch 46 is a single pole, single throw normally open momentaryswitch which is ganged with a normally open momentary switch 47 whichtravels to the off position after contact. A solenoid valve (air valve)58 which although technically part of the air bag itself, is shown herefor completeness, is connected between the opposite contact of switch 56and ground. A timing circuit or timer 65 (e.g., comprising a 7555 orsimilar IC) is connected to the opposite contact of switch 47.

When switch 46 is closed, power is supplied to switch 56 and arms theair bag via the solenoid (air valve) 58. Switch 46 also triggers thetiming circuit 65 via the secondary part of the switch.

The means for sensing that the seat belt system has been placed ininterlocking engagement includes switch 62 which has one contactconnected to line 54a and the opposite contact connected to line 62a.Switch 62 is a normally open switch which is closed when the child's carseat is cinched by the vehicle's seat belt.

Switch 64 is a pressure switch, well known to those skilled in the art,and is normally closed when the pressure required to expand the air bagis present in the propellant canister. One contact of switch 64 isconnected to the first contact of switch 62 and the opposite contact isconnected on line 64a. It will be noted that when a chemical gasgenerating system is employed, switch 64 is omitted.

A voltage detection circuit, generally indicated by the componentswithin the box defined by dotted lines 70 serves to alert the user ifadequate power is not being supplied to the system. A zener diode 72sets a reference voltage and is connected between ground and one of theinput lines of operational amplifier (741 op-amp) 74. The other input ofop-amp 74 senses the actual supply voltage via line 64a. The output ofop-amp 74 is connected to the base of transistor 76. The collector oftransistor 76 is also connected to line 64a and the emitter is one ofthe inputs to AND gate 80'.

An alerter circuit, for sounding the previously mentioned alarm, isgenerally indicated at 80. A piezoelectric alarm buzzer 82 for emittinga second warning signal is actuated when power is supplied to the buzzerunit by the emitter of control transistor 86. If switch 62 is closed(seat belt fastened) when switch 46 is closed, and if the transistor 76is conducting, then the logic AND gate 80' will go high (on) which inturn drives logic AND gate 66 high (on). When the output of the timer 65goes high and AND gate 66 is high, then power is supplied to the melodygenerator 92 by transistor 96.

A device or means for emitting a status signal such as a melodygenerator circuit for playing a first confirming signal or a short tunewhen the air bag is armed and the seat belt is in interlockingengagement is generally indicted by the components within block 90. Acommercially available melody generator 92 is connected to drive speaker94 both of which are driven by drive transistor 96. The emitter oftransistor 96 supplied the input power signal to drive melody generator92 which in turn supplies the current necessary to drive speaker 94.

The melody generator will play until the output of the timer goes low(off). If, on the other hand, switch 62 is open, or air pressure switch64 is open, or transistor 76 is not biased, then the AND gate 80' willbe low (off) which disables gate 66.

In the event that switch 62 is open, or switch 64 is open, or transistor76 is unbiased, the output of AND gate 80' will go low (off). When ANDgate 80' output is low, the output of inverter 76 will go high, biasingtransistor 86 on.

With transistor 86 biased on, power is supplied to the noise generator(alarm) 82. The signal from the noise generator 82 (alarm) is suppliedto transducer 94 which transforms the signal to an audible noise.

Associated with the logic system is a voltage sensing device comprisedof op-amp 74, zener diode 72 and associated resistors. If the voltage tothe system falls below the selected zener diode voltage, op-amp 74 willnot supply enough current to bias transistor 76, which, in turn, willdisable the B input of AND gate 80' thereby causing the alarm 82 tosound.

It will be noted that the foregoing alarm and melody generator could bereplaced or complimented with a visual indicator such as a light 100(see FIGS. 1-3) for the hearing impaired.

In operation, the child's seat 10 is installed in a vehicle by insertingthe seat belt through belt slot openings 36 and inserting the belt intothe buckle opening ensuring that the two components are in lockingengagement. The belt then is tightened, which action will close switch62. In addition, when a child is positioned in the shell 12, switches 46and 47 close. At this point, the circuit will either output a melody viamelody generator 90 indicating that all systems are operating properlyor a warning via buzzer 80 that one of the monitored conditions is in afault mode.

Turning now to the first case, when the air bag equipped car seat isoperating properly, the following conditions must exist, namely, thepower to the system (battery voltage) must be adequate, the pressure inthe gas canister must be adequate, the seat belt system must be inlocking engagement and a child must be seated therein. If any one of theforegoing conditions is not met, then the logic circuit will activatethe alarm buzzer 80 and not the melody generator 90.

A battery voltage sufficient to drive the circuit is defined by zenerdiode 72. The output signal op-amp 74 is proportional to the inputvoltage signal on line 64a and the zener diode voltage inputs thereto. Apower supply voltage at or above the zener diode voltage will cause theop-amp output voltage to drive the base of transistor 76 biasing thetransistor on and causing a current flow from the emitter to thecollector and providing a high input at AND gate 80'. As shown on theschematic, AND gate 80', in order to have a high output signal, mustsimultaneously have all three of its input signals high. In addition, toadequate supply voltage to the circuit, adequate pressure in the gascanister and a connected seat belt system will allow a high input signalon line 62a and lastly a child present in the seat will close switch 46.The foregoing favorable conditions will result in a high output signalfrom AND gate 80' which is also one of the two input signals to AND gate66. The placement of a child in the seat will also temporarily closeswitch 47 activating timer and outputting a high signal for the timedperiod into AND gate 66. Thus, for the period of time that the timer 65is on the output of AND gate 66 will likewise be high driving the baseof transistor 96 which activates the melody generator 92 and speaker 94in order to play the tune which indicates that the system is properlyoperating.

On the other hand, should any one of the foregoing parameters not beoptimal, AND gate 80' will output a low signal which is input intoinvertor 67 and which outputs a high signal. The output signal frominvertor 67 is input into AND gate 68. Also input into AND gate 68 isthe output signal from timer 69 which is high for the timed period. Highinput signals into AND gate 68 from invertor 67 and timer 69 cause ANDgate to output a high signal driving the base of transistor 86 biasingthe transistor on and supplying the current necessary to drive thepiezoelectric warning buzzer 82. Corrective action may then be taken.

FIG. 8 is a schematic representation of a car seat/airbag systemaccording to another embodiment of the present invention. In this carseat/airbag system, a tank 110 of suitable gas or vapor-generatingmaterial, e.g., pressurized air, compressed gas other than air, or vaporpropellant, is connected to solenoid valve 112 to control the flow ofgases from tank 110.

Solenoid valve 112 is actuated by means of an inertial switch 118 whichis powered by battery 120.

A switch and associated output device 122 operates to alert the userthat the car seat is properly installed and in working order. The switchand output device 122 is coupled to a transducer 124, which receivescontrol signal(s) from the switch and output device 122, so that thetransducer provides suitable output, e.g., of an aural (audio) and/orvisual character.

The airbag 126 is coupled with pressurizing medium tank 110 via thesolenoid valve 112 as schematically shown.

In a further aspect, the vehicular seat of this invention may bemodified with a weight sensor element disposed in operative sensingrelationship to the weight-bearing seat surface, and coupled to alarmcircuitry signal arranged to output an alarm signal if the child managesto extricate itself from the seat assembly after the child is initiallyseated and secured in the seat.

Referring now to FIGS. 9 and 10, an alternative configuration of avehicular child safety and restraint system is similar to that of FIGS.1-3, but additionally includes a second pair of openings 36' andassociated seat belt switches 52' for alternatively accommodatingrear-facing mounting of the child safety seat in a vehicle, arestraining harness switch 150, described hereinbelow in greater detail,and an air bag inflator which employs a hermetically stored highpressure compressed inert dry gas propellant.

In overall configuration, the child safety and restraint system of FIGS.9 and 10 is quite similar to that of FIGS. 1-3, and identical referencenumerals are accordingly employed to represent identical orcorresponding elements. The shell portion 12 in FIG. 9 does not havecutouts for the child's legs as in FIG. 1, but, rather, goes straightacross. Correspondingly, the swing down shield 22 is spaced from theshell 12 in FIG. 9, and the locking mechanism 38 in FIG. 1 is replacedby a hold-down strap 38 in FIG. 9.

The hold-down strap 38 is also attached by securing to the shoulderstraps 30 as part of a child-restraining harness, the lower end of whichis connected to a harness lock plate 152. When the harness lock plate152 is inserted into a harness lock mechanism aperture 154, the harnessswitch 150 is activated, as described hereinbelow in greater detail withreference to FIGS. 11A and 11B. A pushbutton 156 is provided forreleasing the harness lock plate 152.

With particular reference to FIG. 10, the buttocks switch 46 is locatedin the lower portion of the shell 12, as in the case of the embodimentof FIGS. 1-3, and is closed when the child's bottom contacts the shell12, thus indicating proper positioning of the child within the seatstructure. However, rather than arming the air bag system as in theembodiment described hereinabove, the buttocks switch 46 in theembodiment of FIGS. 9 and 10 is employed to sense that a child isescaping or is not properly positioned, and the harness switch 150 isemployed to arm the air bag system.

More particularly, the harness switch 150 is activated when the harnesslock plate 152 is properly inserted into the lock mechanism aperture154, and presumably the child is secured within the harness.

The harness lock plate 152 is shown in enlarged view in FIG. 11A, andhas a narrow aperture 156 for attachment of harness webbing (not shownin FIG. 11A) and another aperture 158 which is engaged by either of apair of inclined latch tabs 160 and 162 on a sliding harness lock andrelease plate 164, shown in FIG. 11B. Two latch tabs 160 and 162 areprovided for alternative positioning of the harness lock plate 150depending on the size of the child. FIG. 11B is a top view of thesliding harness lock and release plate 164, while FIG. 11A is a frontelevational view of the harness lock plate 152. One end of the slidingharness lock and release plate 164 comprises the pushbutton 156 visiblein FIG. 9.

A pair of springs 166 are provided for urging the sliding harness lockand release plate 164 in a forward direction (downwardly in theorientation of FIG. 11B), and the harness switch 150 is positioned so asto be activated when the sliding harness lock and release plate is movedrearwardly by insertion of the harness lock plate 152. The configurationis such that the sliding harness lock and release plate 164 reaches itsfull forward limit of travel to deactivate the harness switch 150 whenthe harness lock plate is released. It will be appreciated that suitablehousing and support structure is provided for the sliding harness lockand release plate 164, omitted for clarity of illustration.

In summary, then, there are three types of switches employed in thechild safety and restraint system of FIGS. 9-11. Thus, the buttocksswitch 46 is used to determine whether the child is present and properlypositioned in the seat. There is at least one and preferably there aretwo seat belt sensing switches 52 and 52' in operative association withthe seat structure and the seat belt system of the vehicle, one or theother of which is activated when the seat belt system is in lockingengagement with the child safety and restraint system. Finally, theharness switch 150 is activated when the child is secured within theharness.

With reference to FIG. 12, which is an exploded view, an air bag system,generally designated 170, is located within an enclosure 172, which maybe termed an encapsulation insert, comprising top and bottom plasticshells suitably "welded" together so as to resist tampering. Theenclosure 172 is received within a suitable cavity 174 within the swingdown shield 22. The enclosure 172 has a door 176 which opens when an airbag 178 deploys or inflates, and which accordingly defines an openingthrough which the inflatable air bag 178 projects in a deployedposition.

In order to discourage tampering, an anti-tamper safety switch 180 isphysically connected to the door 176 and is electrically connected asdescribed hereinbelow with reference to FIG. 14 to activate the air bagsystem 170 in the event the door 176 is opened. This effectivelyprevents a system which has been tampered with from being placed inservice. Appropriate warning notices are provided.

The air bag system 170, for convenience of illustration, is shown insolid lines outside the enclosure 172 in FIG. 12 and additionally isshown in dash lines in position within the enclosure 172.

More particularly, the air bag system 170 includes in addition to theair bag 178, an inflator, generally designated 182. The inflator 182 inturn more particularly comprises a pressure tank 184 connected to theair bag 178 through a manifold 186, preferably of aluminum, and asuitable interface 188, preferably of plastic.

Also included within the enclosure 172 are a lithium battery 190 foractivating the air bag system 170, and an inertial sensor 192, such asan acceleration switch, for detecting life threatening front, rear andside collisions. A suitable accelerometer is manufactured by Aerodyne.

Referring now to FIG. 13, in addition to FIG. 12, the pressure tank 184is deep drawn in one piece from 1018 mild sheet steel. The pressure tank184 has a neck 194 which is hot turned and threaded onto the manifold186. By way of example, the volume of the pressure tank 184 isapproximately 8.5 cubic inches, and the storage pressure is 2500 psi.Any suitable gas may be employed, preferably an inert gas. The preferredinert gas is helium, but other suitable inert gases may usefully beemployed, such as argon, nitrogen and mixtures of helium and argon. Forpurposes of comparison, the inflated volume of the air bag 178 is 0.82cubic feet. It will be appreciated that employing a tank 184 of knownvolume storing gas under known pressure results in a controllable andpredictable volume of gas for inflating the air bag 178, avoiding theneed for a dynamic air bag.

Preferably located in the neck 194 of the pressure tank 184 are a pairof frangible membranes 196 and 198, arranged in series for sealing thegas under pressure within the tank 184. The thickness of the disk is0.005 inches, and the preferred diameter is 0.5 inches. Suitable disksare manufactured by Continental Disks of Liberty, Mo.

Positioned between the frangible disks 196 and 198 is a controllabledevice 200 for rupturing the frangible membranes 196 and 198, preferablya pyrotechnic device, which may also be termed a squib, such as a ModelNo. M100, produced by Dyno Nobel, of Mt. Ewing, N.Y.

While in principle a single one of the frangible membranes 196 and 198is sufficient, having the two frangible membranes 196 and 198 allows thepyrotechnic device 200 to be positioned therebetween and renderedessentially inaccessible to prevent tampering.

The frangible membranes 196 and 198 may be welded into the neck 194 ofthe pressure tank 184 itself, or, alternatively, may be included as partof the manifold 186. In any event, during assembly, the tank 184 andmanifold 186 are assembled and sealed together in a hyperbaric chamberat operational pressure. After assembly, the tank 184 and manifold 186are carefully weighed to ensure proper pressure loading. A highsensitivity helium leak test is performed to verify hermetic integrity.

The pyrotechnic device or squib 200 is precisely aligned and mounteddirectly in front of the low pressure side of the frangible membrane196.

The pressure tank 184, frangible membranes 196 and 198, and pyrotechnicsquib device 200 are generally of the same types currently employed invarious manned as well as unmanned space missions. Such devices are keycomponents of life support, safety and emergency escape systems, andhave proven reliability.

Referring finally to FIG. 14, shown is an electrical schematic diagramof an electronics package, preferably included within the shell 12,beneath the seating area. In general, the electronic circuitry of FIG.14 monitors the switches described hereinabove, monitors the operationalstatus of the pyrotechnic squib device 200 and the condition of thelithium battery 190 which powers the pyrotechnic squib device 194, andissues a number of voice status and alarm messages describedhereinbelow.

The circuit of FIG. 14 includes a logic element in the form of aprogrammable microcontroller 220, such as a PIC16C55-XT microcontrollermanufactured by Microchip Devices. In overview, the microcontroller 220monitors the status of the various switches described hereinabove,monitors battery voltages, and serves as the controlling element of avoice message synthesizer, generally designated 222.

Power for the microcontroller 220 and the voice synthesizer 222 issupplied by a 9-volt battery 224 connected to the input of a 5-voltvoltage regulator 226, the output of which supplies operating voltageV_(DD) for the microcontroller 220 and, additionally, through a powerconserving switching circuit 228, supplies operating voltage V_(CC) forthe voice synthesizer 222, as well as operating voltage for variouscomparators.

Inputs to the microcontroller 220 include an input from the buttocksswitch 46, inputs from the two seat belt sensing switches 52 and 52',and an input from one pole 150A of the harness switch 150. These inputsare supplied along respective input lines 230, 232, 234 and 236, towhich pull up resistors (not shown) are also connected, as isconventional.

Power for the pyrotechnic squib device 200 is supplied from the lithiumbattery 190, through a second pole 150B of the harness switch 150 which,when activated, in effect arms the squib 200.

The primary intended switch for supplying power from the battery 190 tothe squib 200 for deploying the air bag 178 (assuming the system 170 isarmed) is the accelerometer 192. However, to discourage tampering bydeploying the air bag 178 rendering a tampered-with system unsuitablefor use, the anti-tampering switch 180 is connected electrically inparallel with the accelerometer switch 192.

For monitoring the squib 200, a resistor 240, for example 10K ohms, isconnected to the 5-volt V_(CC) supply, in series with the squib 200 in avoltage divider configuration. A comparator 242 has its non-inverting(+) input connected to sense the voltage across the squib device 200.For reference purposes, connected to the inverting (-) input of thecomparator 242 is the tap point of a voltage divider comprisingresistors 244 and 246. Under normal conditions, the squib 200 has avoltage drop of approximately 10 to 20 millivolts across its terminals.If the squib 200 were to open circuit, then a voltage of approximately 5volts is developed across the terminals of the squib 200 and appears atthe non-inverting (+) input of the comparator 222, causing the output togo high, to be sensed by an input of the microcontroller 220 along line248.

A pair of battery voltage monitoring circuits 250 and 252 are provided,for respectively monitoring the voltage supplied by the battery 190 forthe squib 200 circuit, and the 9-volt battery 224 for the rest of theelectronics. The battery 190 for the squib 200 is a permanent,non-replaceable part of the child safety and restraint system, and isexpected to last the life of the system.

The 9-volt battery 224, on the other hand, is user-replaceable. It willbe appreciated that, even in the event the battery 224 is completelydead, the air bag can still be armed and deployed under power from thelithium battery 190; the various warning functions, however, would notbe active.

In any event, the two battery monitoring circuits 250 and 252 includerespective comparators 254 and 256 having their inverting (-) inputsconnected to suitable reference voltage dividers 258 and 260. Thelithium battery 190 is connected directly to the non-inverting (+) inputof the comparator 254, and the 9-volt battery 224 is connected to thenon-inverting (+) input of the comparator 256 through a voltage divider262. The various resistor values are selected such that the outputs ofthe respective comparators 254 and 256 go low when the correspondingbattery voltage is low, and the signals are conveyed to inputs of themicrocontroller 220 along lines 264 and 266.

For power conservation purposes, the power switching circuit 228 moreparticularly comprises a P-channel FET transistor having its gateterminal 282 connected to an output 284 of the microcontroller 220, itssource terminal 286 connected to the output of the 5-volt voltageregulator 226, and having its drain terminal 288 connected to supply theV_(CC) supply voltage. A resistor 290, having a typical resistance of100 ohms, is connected between the transistor gate 282 and drain 288terminals. A suitable capacitor 292 or several capacitors in parallelprovides bypassing and power supply decoupling. The microcontroller 220thus selectively enables the supplying of V_(CC) supply voltage to otherportions of the circuit.

The voice synthesizer 222, in addition to the microcontroller 220,comprises an EPROM memory 300 addressed by the microcontroller 220 alonga suitable bus 302, including conventional interface circuits (notshown) such as an address latch. Various voice messages are digitallyrecorded in the EPROM 300. The output of the EPROM 300 is connected tothe input of a digital-to-analog converter 302, the output of whichdrives a suitable audio amplifier 304, which in turn drives a speaker306. The amplifier 304 provides approximately 1/2 watt of audio power toensure the audio is loud enough to be heard over typical noisesgenerated within a vehicle.

Using a 64K byte EPROM 300, a total of eleven seconds of high qualityaudio can be stored, at a sampling frequency of 6 kHz.

Although not illustrated, for prolonging life of the battery 224, itwill be appreciated that various power saving techniques can beemployed, such as a watch dog timer (not shown) whereby themicrocontroller 220 may remain in "sleep mode" most of the time, withthe watch dog timer circuit "waking up" the microcontroller 220 every120 milliseconds or so to check the status of the various inputs.

Considering the operation, in brief overview, various messages areplayed based on the status of various inputs to the microcontroller.More particularly, when the harness switch 150 is activated, the air bagsystem is armed, and various other messages are enabled. In the eventthe harness switch 150, the buttocks switch 46 and either seat beltswitch 52 or 52' is activated, the message "Child is Safe" is generated.In the event the harness switch 150 is activated, but not the buttocksswitch 46, then the message "Child is Escaping" is generated. Althoughnot specifically shown in the drawing figures, a ten-second time delay,for example, may logically be programmed before responding todeactivation of the buttocks switch 46, avoiding a false "child isEscaping" alarm in the event movement of the child results in amomentary opening of the buttocks switch 46. If neither seat belt switch52 or 52' is activated, then a warning "Adjust Seat Belt" is generated.In addition, if the 9-volt battery 224 (also known as battery No. 2) islow, then the message is generated: "Battery Low, Replace Battery."Finally, if either the lithium battery 190 (also known as battery No. 1)is low, or the squib 200 is open circuited, then a message is generated:"Seat Defective, Return to Factory."

It will be appreciated that the decoding of the various inputs and theaddressing of the EPROM memory 300 to output the various messages isreadily accomplished by appropriate programming of the microcontroller220. More particularly, the following Table depicts the programminglogic within the microcontroller 220. In the following Table, the eventnumber is simply provided for convenient reference, and the next sevencolumns represent the status of inputs which result in voice messages.The last five columns indicate which messages are delivered, and howmany times, upon the occurrence of particular conditions.

    __________________________________________________________________________    Voice Message Truth Table                                                     Event                                                                             Inputs                Outputs                                             Number                                                                            HIP SOK                                                                              BS SB1                                                                              SB2 B1                                                                              B2 CIS                                                                              CIE SD                                                                              BL                                                                              AS                                       __________________________________________________________________________    1   1   0  0  0  0   0 0         1                                            2   1   0  0  0  0   0 1         1                                            3   1   0  0  0  0   1 0     2     3 1                                        4   1   0  0  0  0   1 1     2       1                                        5   1   0  0  0  1   0 0         1                                            6   1   0  0  0  1   0 1         1                                            7   1   0  0  0  1   1 0     1     2                                          8   1   0  0  0  1   1 1     1                                                9   1   0  0  1  0   0 0         1                                            10  1   0  0  1  0   0 1         1                                            11  1   0  0  1  0   1 0     1     2                                          12  1   0  0  1  0   1 1     1                                                13  1   0  0  1  1   0 0         1                                            14  1   0  0  1  1   0 1         1                                            15  1   0  0  1  1   1 0     1     2                                          16  1   0  0  1  1   1 1     1                                                17  1   0  1  0  0   0 0         1                                            18  1   0  1  0  0   0 1         1                                            19  1   0  1  0  0   1 0           2 1                                        20  1   0  1  0  0   1 1             1                                        21  1   0  1  0  1   0 0         1                                            22  1   0  1  0  1   0 1         1                                            23  1   0  1  0  1   1 0  1        2                                          24  1   0  1  0  1   1 1  1                                                   25  1   0  1  1  0   0 0         1                                            26  1   0  1  1  0   0 1         1                                            27  1   0  1  1  0   1 0  1        2                                          28  1   0  1  1  0   1 1  1                                                   29  1   0  1  1  1   0 0         1                                            30  1   0  1  1  1   0 1         1                                            31  1   0  1  1  1   1 0  1        2                                          32  1   0  1  1  1   1 1  1                                                   33  1   1  0  0  0   0 0         1                                            34  1   1  0  0  0   0 1         1                                            35  1   1  0  0  0   1 0         1                                            36  1   1  0  0  0   1 1         1                                            37  1   1  0  0  1   0 0         1                                            38  1   1  0  0  1   0 1         1                                            39  1   1  0  0  1   1 0         1                                            40  1   1  0  0  1   1 1         1                                            41  1   1  0  1  0   0 0         1                                            42  1   1  0  1  0   0 1         1                                            43  1   1  0  1  0   1 0         1                                            44  1   1  0  1  0   1 1         1                                            45  1   1  0  1  1   0 0         1                                            46  1   1  0  1  1   0 1         1                                            47  1   1  0  1  1   1 0         1                                            48  1   1  0  1  1   1 1         1                                            49  1   1  1  0  0   0 0         1                                            50  1   1  1  0  0   0 1         1                                            51  1   1  1  0  0   1 0         1                                            52  1   1  1  0  0   1 1         1                                            53  1   1  1  0  1   0 0         1                                            54  1   1  1  0  1   0 1         1                                            55  1   1  1  0  1   1 0         1                                            56  1   1  1  0  1   1 1         1                                            57  1   1  1  1  0   0 0         1                                            58  1   1  1  1  0   0 1         1                                            59  1   1  1  1  0   1 0         1                                            60  1   1  1  1  0   1 1         1                                            61  1   1  1  1  1   0 0         1                                            62  1   1  1  1  1   0 1         1                                            63  1   1  1  1  1   1 0         1                                            64  1   1  1  1  1   1 1         1                                            __________________________________________________________________________     Inputs:                                                                       HIP = Harness ("1" = Harness in Place)                                        SOK = Squib OK ("0" = Squib OK)                                               BS = Baby Seat ("1" = Satisfied)                                              SB1 = Seat Belt #1 ("1" = Satisfied)                                          SB2 = Seat Belt #2 ("1" = Satisfied)                                          B1 = Battery #1 Low ("0" = Low), Lithium                                      B2 = Battery #2 Low ("0" = Low), 9 volt                                       Message Outputs:                                                              CIS = "Child is Safe                                                          CIE = "Child is Escaping                                                      SD = "Seat Defective, Return to Factory                                       BL = "Battery Low, Replace Battery                                            AS = "Adjust Seat Belt                                                   

While the invention has been shown and described herein with referenceto specific features, aspects, and embodiments, it will be recognizedthat numerous variations, modifications, and alternative embodimentsexist, and accordingly all such alternative variations, modifications,and other embodiments are to be regarded as being within the spirit andscope of the present invention.

What is claimed is:
 1. A child safety and restraint system of a typeadapted to be attached in a vehicle to a vehicle seat by fastening of avehicular seat belt system thereto, said child safety and restraintsystem comprising:a seat structure having a harness releasably securedto said seat structure; a first sensing device mounted to said seatstructure, said first sensing device being activated when it senses apresence of a child positioned within said seat structure; a secondsensing device mounted to said seat structure, said second sensingdevice being activated when it senses that said seat structure issecured to said vehicle seat by locking engagement of said vehicularseat belt system; a third sensing device mounted to said seat structure,said third sensing device being activated when said harness is securedto said seat structure; and a device for emitting a first audibleindication after said first, second, and third sensing devices have beenactivated.
 2. The child safety and restraint system according to claim 1wherein said first direct indication is a synthesized voice delivering afirst message.
 3. The child safety and restraint system according toclaim 1 further comprising a device for emitting a second directindication when said first sensing device has been deactivated afterfirst being activated.
 4. The child safety and restraint systemaccording to claim 3, wherein said second direct indication is asynthesized voice delivering a second message.
 5. The child safety andrestraint system according to claim 3 further comprising a device foremitting a third direct indication when said second sensing device hasbeen deactivated after first being activated.
 6. The child safety andrestraint system according to claim 5 wherein said third directindication is a synthesized voice delivering a third message.
 7. Thechild safety and restraint system according to claim 1 furthercomprising a device for emitting a second direct indication that saidsecond sensing device has been deactivated after first being activated.8. The child safety and restraint system according to claim 7 whereinsaid second direct indication is a synthesized voice delivering a secondmessage.
 9. A child safety and restraint system of a type adapted to beattached in a vehicle to a vehicle seat by fastening of a vehicular seatbelt system thereto, said child safety and restraint system comprising:aseat structure; a harness mounted to said seat structure, said harnessbeing selectively movable between an open position and a closedposition; a first sensing device mounted to said seat structure, saidfirst sensing device being activated when it senses a presence of achild positioned within said seat structure; a second sensing devicemounted to said seat structure, said second sensing device beingactivated when it sensed that said seat structure is secured to saidvehicle seat by locking engagement of said vehicular seat belt system; athird sensing device associated with said harness, said third sensingdevice being actuated when said harness is in said closed position; anda device for emitting a first audible indication after said first,second, and third sensing devices have been actuated.
 10. The childsafety and restraint system according to claim 9 wherein said firstdirect indication is a synthesized voice delivering a first message. 11.The child safety and restraint system according to claim 9 furthercomprising a device for emitting a second direct indication when saidfirst sensing device has been deactivated after first being activated.12. The child safety and restraint system according to claim 11, whereinsaid second direct indication is a synthesized voice delivering a secondmessage.
 13. The child safety and restraint system according to claim 11further comprising a device for emitting a third direct indication whensaid second sensing device has been deactivated after first beingactivated.
 14. The child safety and restraint system according to claim13 wherein said third direct indication is a synthesized voicedelivering a third message.
 15. The child safety and restraint systemaccording to claim 9 further comprising a device for emitting a seconddirect indication that said second sensing device has been deactivatedafter first being activated.
 16. The child safety and restraint systemaccording to claim 15 wherein said second direct indication is asynthesized voice delivering a second message.
 17. A child safety andrestraint system of a type adapted to be attached in a vehicle to avehicle seat by fastening of a vehicular seat belt system thereto, saidchild safety and restraint system comprising:a seat structure; a harnessmounted to said seat structure, said harness being selectively movablebetween an open position and a closed position; a first sensing devicemounted to said seat structure, said first sensing device being operableto detect a presence of a child positioned within said seat structure; asecond sensing device mounted to said seat structure, said secondsensing device being operable to detect when said seat structure issecured to said vehicle seat by locking engagement of said vehicularseat belt system; a third sensing device associated with said harness,said third sensing device being operable to detect the position of saidharness; and a device for emitting a first audible indication after saidfirst sensing device senses the presence of a child, said second sensingdevice sensing that said seat structure is secured to said vehicle seatand said third sensing device senses that said harness is in said closedposition.
 18. The child safety and restraint system according to claim17 further comprising a device for emitting a second direct indicationwhen said first sensing device detects an absence of said child afterfirst having sensed said presence of said child.
 19. The child safetyand restraint system according to claim 17 further comprising a devicefor emitting a second direct indication when said second sensing devicedetects that said seat structure is not secured to said vehicle afterfirst having sensed that said seat structure was secured to saidvehicle.
 20. The child safety and restraint system according to claim 17further comprising a device for emitting a second direct indication whensaid harness moves from said closed position to said open position.